Abstract: A spacer device (30) for use in a cavity wall of a building to determine the separation of the building elements of the two leaves (19,20) of the wall during construction, comprising a support body (31) having a plurality of spaced projections (32) extending transversely of the general plane of the support body and, in use, across the cavity between the said two leaves, each projection having means for preventing or at least inhibiting the transfer of moisture at least in one direction from one end of the projection to the other.